Servlet 中实现验证码

最新推荐文章于 2025-04-25 15:48:34 发布

原创最新推荐文章于 2025-04-25 15:48:34 发布 · 759 阅读

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文章标签：

#servlet #random #session #image #string #class

本文介绍了一个使用Servlet实现验证码功能的示例，包括生成随机颜色、背景线条和4位随机码，将验证码存入Session中，并通过JSP进行展示。

Servlet 中实现验证码

package com.admincontrol;

import java.awt.Color;
import java.awt.Font;
import java.awt.Graphics;
import java.awt.image.BufferedImage;
import java.io.IOException;
import java.util.Random;

import javax.imageio.ImageIO;
import javax.servlet.ServletException;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import javax.servlet.http.HttpSession;

@SuppressWarnings("serial")
public class GetRandNum extends HttpServlet{
private final int width = 60;
private final int height = 18;
protected void doGet(HttpServletRequest request, HttpServletResponse response)
throws ServletException, IOException {
this.doPost(request, response);
}
protected void doPost(HttpServletRequest request, HttpServletResponse response)
throws ServletException, IOException {
request.setCharacterEncoding("UTF-8");
response.setContentType("image/jpeg");
HttpSession session = request.getSession();
response.setHeader("Pragma","No-cache");
response.setHeader("Cache-Control","no-cache");
response.setDateHeader("Expires", 0);
BufferedImage image = new BufferedImage(width,height,BufferedImage.TYPE_INT_RGB);
Graphics gs = image.getGraphics();
Random random = new Random();
gs.setColor(getRandColor(200,250));
gs.fillRect(0, 0, width, height);
//定义字体形式
gs.setFont(new Font("Times New Roman",Font.PLAIN,18));
//用线条画背景
gs.setColor(getRandColor(160,200));
for(int i=0;i<155;i++) {
int i_x = random.nextInt(width);
int i_y = random.nextInt(height);
int i_xl = random.nextInt(12);
int i_yl = random.nextInt(12);
gs.drawLine(i_x,i_y,i_x+i_xl,i_y+i_yl);
}
//产生4位随机码
String yzm_Rand="";
String str ="0123456789abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWSYZ";
char[] ch = new char[4];
for(int i=0;i<4;i++) {
int n = new Random().nextInt(62);
ch[i] = str.charAt(n);
yzm_Rand += String.valueOf(ch[i]);
gs.setColor(new Color(
20+random.nextInt(110),
20+random.nextInt(110),
20+random.nextInt(110)));
gs.drawString(String.valueOf(ch[i]),13*i+6,16);
}
//将验证码存入Session中
session.setAttribute("yanzhenma",yzm_Rand);
gs.dispose();
ImageIO.write(image, "JPEG", response.getOutputStream());
}
//获取随机颜色
public Color getRandColor(int cc,int bb) {
Random random = new Random();
if(cc>255) cc=255;
if(bb>255) bb=255;
int r=cc+random.nextInt(bb-cc);
int g=cc+random.nextInt(bb-cc);
int b=cc+random.nextInt(bb-cc);
return new Color(r,g,b);
}
}